164 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
of which may be termed the Montpelier, the Bowden, the Manchioneal, 
and the Pleistocene subsidences, and the succeeding elevations the Mid- 
Oligocene, the late Miocene, and the early Pleistocene, or recent elevar 
tions respectively. It is interesting to note that these movements are 
each successively smaller in amplitude than the preceding, like the dying 
strokes of the pendulum. 5 
The orogenic or mountain folding movements were especially charac” 
teristic of the earlier of the middle periods of its history, while the 
epeirogenic events mark the later stages. The Post-Richmond, Post- 
Moneague, and Post-Bowden uplifts were all of an orogenic characte! 
but each successively consisting of broader arching and less closely 
folded deformation. Thus it is that the Richmond beds are closely. 
folded and overthrown, the Cambridge, Montpelier, and Moneague beds 
arched and gently wrinkled, the Bowden beds only tilted. Collectively: 
they probably represent the initiation, culmination, and expiration © 
the great Antillean mountain uplifts, The elevated reefs recording 
the epeirogenic movements were horizontally elevated without visible 
deformation. 
An interesting fact of the structure of Jamaica, as well as the Antilles 
in general, are the two lines of orogenic dominant trends, one extending 
northwest and southeast, and the other east and west. Whether these 
trends can be each associated with a peculiar effort of mountain making 
we cannot form definite conclusions at present. VU 18 very probable 
however, that all of the structure was originally dependent upon an an 
cient, early Mesozoic orographie uplift or buttress, which had an east W 
west axis through the Great Antilles and the Guatemala-Chiapas region 
the only trace of which is now preserved in the old Post-Paleozoic mou” 
tains of the latter region and possibly Western Cuba. It is certai 
however, that the earliest movements visible in the present structure a 
Jamaica had a northwest and southeast trend conformable to the din? 
tion of the present Blue Mountain ridge, and conformable to simila! 
trends in the combined coast line of northeast Cuba and Maiti and t 
outer margin of the Bahama Banks. The later movements have i 
and west trends (which might be called Antillean), as shown in d 
secondary axis of the elevated limestone ridges of Jamaica, Cuba, Pet 
Rico, and the structuro of the base of the Yucatan peninsula, the mon 
tains of Eastern Honduras, the Isthmus of Panama, and the Vonezuel® 
coast. It may be well to note here that it is impossible at, present to 
into either of these systems of trends — the Bahaman or Antillea? 
all the Windward Islands or their submarine platforms. 
